1. Technical Field
The present disclosure relates to surgical procedures for ablating tissue. More specifically, the present disclosure is directed to the use of a planning system to determine a treatment plan and a navigation system to effect a treatment plan for an ablation procedure.
2. Background of the Related Art
Electrosurgical devices have become widely used. Electrosurgery involves the application of thermal and/or electrical energy to cut, dissect, ablate, coagulate, cauterize, seal or otherwise treat biological tissue during a surgical procedure. Electrosurgery is typically performed using a handpiece including a surgical device (e.g., end effector or ablation probe) that is adapted to transmit energy to a tissue site during electrosurgical procedures, a remote electrosurgical generator operable to output energy, and a cable assembly operatively connecting the surgical device to the remote generator.
Treatment of certain diseases requires the destruction of malignant tissue growths, e.g., tumors. In the treatment of diseases such as cancer, certain types of tumor cells have been found to denature at elevated temperatures that are slightly lower than temperatures normally injurious to healthy cells. Known treatment methods, such as hyperthermia therapy, typically involving heating diseased cells to temperatures above 41° C. while maintaining adjacent healthy cells below the temperature at which irreversible cell destruction occurs. These methods may involve applying electromagnetic radiation to heat, ablate and/or coagulate tissue. There are a number of different types of electro surgical apparatus that can be used to perform ablation procedures.
Minimally invasive tumor ablation procedures for cancerous or benign tumors may be performed using two dimensional (2D) preoperative computed tomography (CT) images and an “ablation zone chart” which typically describes the characteristics of an ablation needle in an experimental, ex vivo tissue across a range of input parameters (power, time). Energy dose (power, time) can be correlated to ablation tissue effect (volume, shape) for a specific design. It is possible to control the energy dose delivered to tissue through microwave antenna design, for example, an antenna choke may be employed to provide a known location of microwave transfer from device into tissue. In another example, dielectric buffering enables a relatively constant delivery of energy from the device into the tissue independent of differing or varying tissue properties.
After a user determines which ablation needle should be used to effect treatment of a target, the user performs the treatment with ultrasound guidance. Typically, a high level of skill is required to place a surgical device into a target identified under ultrasound. Of primary importance is the ability to choose the angle and entry point required to direct the device toward the ultrasound image plane (e.g., where the target is being imaged).
Ultrasound-guided intervention involves the use of real-time ultrasound imaging (transabdominal, intraoperative, etc.) to accurately direct surgical devices to their intended target. This can be performed by percutaneous application and/or intraoperative application. In each case, the ultrasound system will include a transducer that images patient tissue and is used to identify the target and to anticipate and/or follow the path of an instrument toward the target.
Ultrasound-guided interventions are commonly used today for needle biopsy procedures to determine malignancy of suspicious lesions that have been detected (breast, liver, kidney, and other soft tissues). Additionally, central-line placements are common to gain jugular access and allow medications to be delivered. Finally, emerging uses include tumor ablation and surgical resection of organs (liver, lung, kidney, and so forth). In the case of tumor ablation, after ultrasound-guided targeting is achieved a biopsy-like needle may be employed to deliver energy (RF, microwave, cryo, and so forth) with the intent to kill tumor. In the case of an organ resection, intimate knowledge of subsurface anatomy during dissection, and display of a surgical device in relation to this anatomy, is key to gaining successful surgical margin while avoiding critical structures.
In each of these cases, the ultrasound-guidance typically offers a two dimensional image plane that is captured from the distal end of a patient-applied transducer. Of critical importance to the user for successful device placement is the ability to visualize and characterize the target, to choose the instrument angle and entry point to reach the target, and to see the surgical device and its motion toward the target. Today, the user images the target and uses a high level of skill to select the instrument angle and entry point. The user must then either move the ultrasound transducer to see the instrument path (thus losing site of the target) or assume the path is correct until the device enters the image plane. Of primary importance is the ability to choose the angle and entry point required to direct the device toward the ultrasound image plane (e.g., where the target is being imaged).